This invention relates to a device for generating useful heat from solar radiations, including a black surface positioned on a support which is in heat conducting contact with a flowable heat carrying medium contained in a pipe conduit having an inlet and an outlet.
Known devices of this type include, as stationary equipment, a sheet metal plate which constitutes the carrier for a black surface and from which the heat is transmitted to water that contacts the underside of the sheet metal plate.
In the weekly periodical "VDI-Nachrichten" of July 4th, 1975, on pages 1 and 9, there is described a device for generating useful heat from solar radiation by means of black conduits accommodating a flowable heat carrier medium. The black conduits extend in jackets which are pervious to solar rays but which reduce heat transfer to the environment. More particularly, according to this publication, there are provided two absorber tubes with black glass enamel which are spaced from one another in an evacuated protective tube which is pervious to solar radiation and which at its upper portion, i.e., the portion oriented towards the sun has an inner heat reflecting filter, while its lower portion, which is oriented away from the sun, is provided with a silver mirror. One of the absorber tubes is provided for the inlet and the other for the outlet of the heat carrying water. A plurality of such arrangements are provided in a side-by-side contacting arrangement.
The above-outlined known device, although of high efficiency, is very expensive and further has the disadvantage that it is not portable: for shipment, the device must be disassembled.